(1) Field of the Invention
The present invention relates to an apparatus for carrying out fuzzy inference with an oblivescence function and method therefor.
(2) Background Art
The concept of fuzzy logic can be said to be a high level of thinking even though it is indefinite. For example, a machine operator (expert) has plenty of know-how on the machine's method of operation, such know-how consists primarily of quantitative emprical rules. However, to utilize such emprical rules, fuzzy inference has been proposed such that quantitative emprical rules are expressed in fuzzy terms or fuzzy sets as qualitative values using linguistic control rules (LCRs, if--is--, then--is--) and inference is executed on the basis of the linguistic control rules of expression.
A Japanese document named "introduction of fuzzy engineering (Fuzzy Engineering Nyuumon)" published on Jul. 15, 1989 exemplifies a control system using fuzzy inference to the tunnel trenching in a shield construction method.
In such a system utilizing fuzzy inference, it is important to aquire rules (knowledge) and to deal with each rule equally.
On the other hand, a machine operator, or other such skilled person (expert), may change his or her methods depending on date (or time of year), location, and/or situation and makes decisions in conformity to his or her state.
As a basic example, as to enviroment, a water temperature which would be assigned a qualitative value of warm in a cold winter, may be considered cool in a hot summer, or in regard to a state or condition, an object which may be considered light by an energetic person may be heavy to a tired person. These are qualitative operating variables utilized naturally by human beings. This means that some rules (knowledge or qualitive assumptions) may become dim, or disregarded due to oblivescence while some rules are called upon and utilized without oblivescence
A system of fuzzy inference utilizing such principles has been proposed to be applied for controlling automatic dredging and/or tunnel trenching apparatus.
However, in previously proposed fuzzy inference systems, such functions as oblivescence or reproduction of knowledge are ignored and thus a serious defect is present for structuring a truly human friendly system (or problem solving supporting system).